First Simultaneous Determination of Inclusive and Exclusive |V_ub |

The first simultaneous determination of the absolute value of the Cabibbo-Kobayashi-Maskawa matrix element Vub using inclusive and exclusive decays is performed with the full Belle data set at the (4S) resonance, corresponding to an integrated luminosity of 711 fb-1. We analyze collision events in which one B meson is fully reconstructed in hadronic modes. This allows for the reconstruction of the hadronic Xu system of the semileptonic b→uν¯ decay. We separate exclusive B→πν¯ decays from other inclusive B→Xuν¯ and backgrounds with a two-dimensional fit that utilizes the number of charged pions in the Xu system and the four-momentum transfer q2 between the B and Xu systems. Combining our measurement with information from lattice QCD and QCD calculations of the inclusive partial rate as well as external experimental information on the shape of the B→πν¯ form factor, we determine |Vubexcl|=(3.78±0.23±0.16±0.14)×10-3 and |Vubincl|=(3.88±0.20±0.31±0.09)×10-3, respectively, with the uncertainties being the statistical error, systematic errors, and theory errors. The ratio of |Vubexcl|/|Vubincl|=0.97±0.12 is compatible with unity.